People with diabetes may be at higher risk for cardiovascular problems when air pollution levels are higher, according to a new study of Boston-area residents. The ability of the blood vessels to control blood flow was impaired in adults with diabetes on days with elevated levels of particles from traffic and coal-burning power plants.
The researchers evaluated several kinds of fine particles found in urban air pollution. These included sulfate particles, which come mainly from coal-burning power plants, as well as ultra-fine particles and black carbon soot, which are generated primarily by diesel- and gasoline-powered vehicles.
"Our strongest finding was that blood vessel reactivity was impaired in people with diabetes on days when concentrations of sulfate particles and black carbon were higher," said Marie O'Neill, Ph.D., an epidemiologist now with the Robert Wood Johnson Health & Society Scholars program at University of Michigan and lead author on the study. "Impaired vascular reactivity has been associated with an increased risk of heart attack, stroke and other heart problems."
"Previous studies have shown that when air pollution levels are higher, people with diabetes have higher rates of hospitalization and death related to cardiovascular problems," said NIEHS Director David Schwartz, M.D. "These changes in blood vessel reactivity may help explain this phenomenon."
The National Institute of Environmental Health Sciences, one of the National Institutes of Health, provided funding to O'Neill and other researchers at the Harvard School of Public Health for the study. Other collaborators were from the Joslin Diabetes Center and Beth Israel Deaconess Medical Center in Boston. The findings are published in the June 2005 issue of the journal Circulation.
"We don't really understand why fine particles may cause this decrease in vascular reactivity," said O'Neill. "Further research is needed to confirm this association between air pollution and vascular health and to understand what causes people with diabetes to be especially sensitive."
Researchers recruited 270 greater Boston metropolitan residents and divided them into two groups. The first group consisted of subjects with a positive diagnosis of type I or type II diabetes. The second group included subjects who were not diabetic, but who had a family history of diabetes or blood sugar levels slightly higher than normal.